Question

A man can row a boat in still water with a velocity of 8kmph. Water is flowing in a river with a velocity of 4kmph. At what angle should he row the boat so as to reach the exact opposite point ?

plz answer this

Answer 1

Answer:

Explanation:

The boat in still water can move with velocity 8kmph and the water flowing with 4kmph

So we have to use sintetha and at last the angle they asked

So we should use alpha =90+the angle we found before

Then the answer will come with degrees

Answer 2

Explanation:

Given that,

 The velocity of the boat in still water is 8 kmph

  The velocity of the flowing water is 4 kmph

So, Here we are using sin θ and we also find the angle.

So, we will use $\alpha$ = $90^o+$ angle we got

The answer will be in degrees $(^o)$ since we need to find angle.

Here we use,

$sin \theta=\frac{Opposite \ Side}{Hypotenuse}$

$sin \theta=$ Velocity of river/ Velocity of boat

$sin \theta= \frac{4}{8}$

$sin \theta= \frac{1}{2}$      $[\because sin 30^o = \frac{1}{2}]$

$\theta= 30^o$

And the $\alpha = 90^o+$ angle we got

$\therefore \alpha = 90^o+30^o$

$\Rightarrow \alpha = 120^o$

∴ At the angle of $120^o$ he should row the boat so, as to reach the exact opposite point.